In order to solve veracious measurement about the variety of extinguishing agent concentration along with time in the ground simulation test of helicopter/aeroplane powerplant compartment, the special extinguishing agent concentration measurement has been developed. The project includes the principle, the system composition, the rapid air heating, the differential pressure generation and the multichannel synchronous control. The measurement has been successfully used in the ground simulation test of several helicopters, the datum show the response of measurement is real-time about the variety of extinguishing agent concentration along with time, because of response sensitivity. it can be satisfied with the requirement of ground simulation test in the fire extinguisher system of helicopter/aeroplane powerplant compartment.